Gas turbines generally include a turbine rotor (often referred to as a wheel) with a number of buckets (or blades) circumferentially attached to the rotor by dovetails. The buckets may project into the hot gas path to convert the kinetic energy of the gas into rotational mechanical energy. To avoid overheating and damaging the buckets, cooling air can be introduced into passages that extend radially through the bucket. One of the challenges associated with cooling the bucket is to keep the cool air from leaking through the gap between the tabs of the dovetails and the surface of the rotor, particularly during operation and under conditions of centrifugal loads and thermal expansion. When air leaks into the wheel space, it may be necessary to increase the cooling airflow to maintain the bucket cooling requirements. Consequently, the output and overall efficiency of the turbine may be reduced, for example, due to the extra load on the cooling air compressors.